标题： 单分子电致发光及其之外 显示英文标题

标题： Single-molecule Electroluminescence and Beyond

摘要： 扫描隧道显微镜（STM）的功能不仅限于原子成像和操控。 其隧穿电流也可用于光的激发，将电子能量转换为光子能量。 通过采用高效的电子解耦和纳米腔等离激元增强相结合的策略，可以实现基于STM的单分子电致发光。 在优化分子、间隔层、探针和基底的材料组合后，发射强度可以足够强且稳定，以进行二阶光子关联测量。 观察到明显的光子反聚束效应，清楚地证明了单分子电致发光的单光子发射特性。 值得注意的是，当通过STM操控人工构建分子二聚体时，发现单体的光谱峰会发生分裂，这表明来自隧穿电子的激发能量可能在整分子二聚体上迅速离域。 通过亚纳米分辨率的电致发光成像技术，可以在实空间中可视化二聚体中不同能态的激子耦合的空间分布，这与基于相干分子间偶极-偶极耦合预测的局部光学响应高度相关。 此外，单个分子还可以与等离激元纳米腔产生相干耦合，从而导致干涉诱导的法诺共振的发生。 这些发现为在单分子水平上制造电驱动的量子光源以及研究分子间能量转移、场-物质相互作用和分子光电学提供了新的途径。 显示英文摘要

摘要： A scanning tunneling microscope (STM) can do more than atomic imaging and manipulation. Its tunneling current can also be used for the excitation of light, converting electron energy to photon energy. STM based single-molecule electroluminescence can be realized by adopting a combined strategy of both efficient electronic decoupling and nanocavity plasmonic enhancement. The emission intensity, upon optimized material combination for the molecule, spacer, tip, and substrate, can be strong and stable enough for performing second-order photon correlation measurements. The observation of an evident photon antibunching effect demonstrates clearly the nature of single-photon emission for single-molecule electroluminescence. Strikingly, the spectral peak of a monomer is found to split when a molecular dimer is artificially constructed through STM manipulation, which suggests that the excitation energy from tunneling electrons is likely to rapidly delocalize over the whole molecular dimer. The spatial distribution of the excitonic coupling for different energy states in a dimer can be visualized in real space through sub-nanometer resolved electroluminescence imaging technique, which correlates very well with the local optical responses predicted in terms of coherent intermolecular dipole-dipole coupling. Furthermore, a single molecule can also couple coherently with a plasmonic nanocavity, resulting in the occurrence of interference-induced Fano resonance. These findings open up new avenues to fabricate electrically driven quantum light sources as well as to study intermolecular energy transfer, field-matter interaction, and molecular optoelectronics, all at the single-molecule level.